Railway traffic controlling apparatus



Oct. 10, 1961 c. w. FAlLOR RAILWAY TRAFFIC CONTROLLING APPARATUS 2 Sheets-Sheet 1 Filed Feb. 21, 1958 when padlock 61$ removed.

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RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Feb. 21, 1958 2 Sheets-Sheet 2 if! Q T V TR 1V 6' a: B 1477 5 41 I a Mpmallg Qaen onacs' clased a/bea padlock is removed.

INVENTOR. U/ZQPZQS W mp aired states 3,034,151 Patented Get. 10, 1 961 3,004,151 RAILWAY TRAFFIC CONTROLLING APPARATUS Charles W. Failor, Forest Hills, Pa, assignor to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Filed Feb. 21, 1958, Ser. No. 716,586 12 Claims. (Cl. 245-146) My invention relates to railway trafiic controlling apparatus, and particularly to an arrangement for coordinating the operation of an outlying track switch with a signal controlling traflic movement over the switch.

In railway signaling and traffic controlling systems, it is the practice to control the signals governing train movements over outlying track switches, that is, switches outside of yards and interlocking plants, to give their stop indications when the switches become misplaced. This is accomplished by providing such switches with circuit controllers and circuit arrangements through contacts of the circuit controller associated with each switch.

Such switches are usually manually operable and protected against operation by unauthorized persons by means of padlocks which may be opened by keys carried by certain selected railway presonnel. It is sometimes necessary or desirable to supplement the protection obtained from the use of a padlock, by adding another switch lock which may be controlled manually from a remote point or automatically in accordance with trafiic conditions, etc. For example, when a switch is associated with a main track provided with an automatic signal system, a common method is to provide a time control for the switch lock. The switch is then provided with signal controlling contacts which are operable, when the padlock is removed, to control the signal or signals controlling train movements over the switch to give their stop indications. The time control may be either electrical or mechanical and is started at the same time the signals are set to stop. The switch lock is released at the expiration of a predetermined time. This period of time is so selected that a train approaching the switch is either stopped by the signal governing movements over the switch or, if a train has already passed such signal, the train will have time to proceed past the switch before an unlock is obtained. These switch locks, and methods for control thereof, are well known in the railway signaling art.

The controlling of the signals to give their stop indication, when an outlying switch becomes misplaced or when a padlock is removed from a switch, maly be accomplished through the use of line circuits controlled by the aforesaid switch circuit controller contacts or padlock controlled contacts. However, for economic and maintenance reasons it is usually desirable to eliminate the line circuits and, where track circuits are employed, to shunt the track rails by means of circuits through the switch circuit controller or padlock controlled contacts. Also in cab-signaling territory it is necessary to remove the cab-signal energy from the rails when an outlying switch becomes misplaced or when a padlock is removed from a switch provided with a switch lock. This may be accomplished by shunting the track rails, or by use of line circuits to disconnect the source of cab-signal energy being supplied to the rails. If, however, a train has just passed an outlying switch and the cab-signal energy is removed from the rails by disconnecting the source of the energy by the line circuit control method, an improper restricting cab-signal for the train will result. It is thus apparent that the shunting of the track circuit is the preferred method vfor control. This method causes release of the track relay associated with the shunted track circuit, thereby controlling the signal or signals governing train movements over the section of track to give their stop indication.

In territory where electrical propulsion systems are utilized to provide the motive power for propulsion of trains, the track shunting contacts must be made sufficiently large to carry any flow of propulsion current which might take place because of a dilierence in potential between the rails. In such cases, the size of the con tacts required and consequently the size of the housing for the contacts may be so great as to over-balance the aforesaid economic and maintenance disadvantages of the line circuits for control of the signals.

Accordingly, one object of my invention is to provide an arrangement, operated by relatively light-weight electrical contacts, [for applying a shunt to a railway track circuit in electric propulsion territory where steady or coded A.C. track circuits are utilized for signal control.

A second object of my invention is to provide an arrangement for applying a shunt to a railway track circuit in electric propulsion territory where steady or coded A.C. track circuits are utilized, without the use of electrical contacts directly in the shunt circuit, thereby eliminating the necessity for heavy-duty contacts.

A third object of my invention is to provide, at an outlying switch arranged with a switch lock, a means for applying a shunt to a steady or coded A.C. railway track circuit without the use of electrical contacts directly in the shunt circuit, and to provide apparatus for checking the integrity of said shunting means before an unlock of said switch can be obtained.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

In accomplishing the foregoing objects of my invention, I employ a saturable reactor as a shunting device or means for shunting the track circuits, and a relay or relays in conjunction with the shunting means for checking the integrity of the reactor and associated circuitry.

I shall describe three forms of apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the drawings:

FIG. 1 is a diagrammatic view showing one form of apparatus embodying my invention using a saturable reactor with three windings, and a single winding checking relay.

FIG. 2 shows a modification of the arrangement of FIG. 1 using a saturable reactor with four windings, a single winding checking relay, and a double winding checking relay.

FIG. 3 shows an arrangement similar to FIG. 2 but in which the single winding checking relay is eliminated.

In each of the views similar reference characters refer to corresponding parts.

Referring first to FIG. 1, a section of main railway track T is shown connected with a siding track AT by a hand-operated switch SW. An alternating current track circuit is provided for this section of track which includes a relay TR connected across the rails at one end of the section, and a means for providing a suitable alternating current, here shown as a track transformer TT, connected across the rails adjacent the other end of the section.

A traflic controlling device here shown as a signal S is located adjacent the relay end of the track section T for governing traflic movements in an eastward direction or to the right, as shown in the drawings by the arrow within track section T. The control circuit for signal S is shown as including only a front contact of relay TR in order to make this description as simplified as possible. Signal S may be any of the well known types such as the search-light type and as here shown the signal displays but two aspects, red or green for indicating stop or proceed, respectively.

It is expedient to point out at this time that energy for illumination of the signal lamp and operation of the signal mechanism at the signal location, and for operation of the apparatus at the switch location is furnished by a suitable source of direct current at each location, such as a battery of proper voltage and current. For the sake of simplicity these sources of current are not shown in the drawings, and their positive and negative terminals are identified by the reference characters B and N, respectively. A source of alternating current the terminals of which are designated BX and CX is also provided at the track transformer location for supplying energy to the primary winding of track transformer T1.

Switch SW is shown provided with an electrically operated switch lock SWL the control winding of which is designated by the reference character WLK. Switch locks are well known in the railway signaling art and may be, for example, similar to that shown in Letters Patent of the United States No. 2,517,280, issued August 1, 1950, to Herbert L. Bone, George L. Temple and John W. Logan, J r. Such switch locks are provided with electrical contacts which are normally open, but close when the padlock for mechanically locking the switch is removed therefrom. These padlock contacts are designated in the drawings as PDLa and PDLb.

Switch SW is also provided with a switch circuit controller SWC, provided with normally open contacts which are operated to a closed position when the switch moves or is moved from its normal position. Switch SW is normally aligned for a train movement over the main track T.

There is also shown in FIG. 1 a saturable reactor SRA comprising a winding arrangement in which stray flux is kept to a minimum. The first windings W1 and WlA are the main or load windings and are connected to each other in series. The remaining terminals of the windings are connected to opposite rails of track section T. These windings are identical and are so proportioned to normally introduce a high reactance between the rails of the track section. Under normal conditions this reactance is not low enough for the windings to shunt the track circuit of track section T. Reactor SRA is also provided with a second winding W2 which is an auxiliary or con trol winding. The operation of this control winding will be set forth later in this description.

A time delay device, here shown as a timing relay TER, and a single winding check relay TESRA are provided at the switch for controlling the unlocking of the switch lock by energization of the control winding WLK of the switch lock.

The apparatus is shown in the condition it occupies under normal conditions, that is, when there are no trains in track section T, and switch SW is in its normal position and locked in that position by the padlock and the electric switch lock SWL. Under these conditions track relay TR is energized and signal S is displaying its green aspect to permit a train to enter track section T. Signal S is controlled over front contact a of track relay TR and it is to be understood that signal S will display its green aspect when relay TR is picked up and its red aspect when that relay is released. This signal control circuit is obvious from the drawings and no detailed description thereof is deemed necessary.

I will first assume that the apparatus is in its normal condition as shown and described and that a train in the siding track AT is to move over switch SW into the main track T. The padlock is removed from the switch causing the padlock actuated contacts PDLa and b to close. The closing of contact PDLa completes a circuit for picking up relay TESRA. This circuit may be traced from battery terminal B through padlock actuated contact PDLa, control winding W2 of saturable reactor SRA, back contact b oftiming relay TER, and the winding of relay TESRA to battery terminal N. This completed circuit also intro duces a direct or unidirectional current flow in the winding W2 and the whole core structure of reactor SRA is magnetized. As saturation of the core is approached, the eifective permeability of the iron core is reduced and the reactance of the windings W1 and W2 is reduced accordingly. It follows that the reactance of the windings W1 and WllA of reactor SRA is controlled by the application or removal of direct current to or from the winding W2 of reactor SRA. The application of direct current to winding W2 sufficiently lowers the reactance of the windings W1 and WlA to permit an effective portion of the alternating current flowing in the rails of track section T to flow through said windings, thus shunting the track circuit of the track section. The shunting of the track circuit causes relay TR to release and control signal S to display its red aspect.

The energization of relay TESRA, as described above, checks that the direct current is supplied to winding W2 thereby shunting the track circuit of track section T, before relay TESRA can pick up and begin a timing cycle for release of the switch lock Back contact b of relay TER in the pick-up circuit of relay TESRA checks that relay TER occupies its normal position before the beginning of a timing cycle, and that the full timing period will thus be obtained before relay TER will close its front contact a. Relay TESRA is also provided with a stick circuit over its own front contact a to maintain that relay picked up when relay TE-R begins its timing cycle and opens its back contact 17. This stick circuit is believed obvious and no detailed description thereof is necessary.

The picking up of relay TESRA completes a circuit for energize-tion of timing relay TER and starts the timing cycle. The circuit for energization of relay TER may be traced from battery terminal B through padlock actuated contact PDLb, front contact b of relay TESRA and the winding of timing relay TER to battery terminal N. When the timing period of relay TER has expired, a circuit for energizatlon of the switch lock control winding WLK is completed and an unlock is obtained. This circuit may be traced from battery terminal B through contact PDLb, front contact I) of TESRA, front contact a of relay TER and winding WLK to battery terminal N. Switch SW is now unlocked and may be operated to its reverse position for the train to move from the siding track AT to the main track T.

The moving of the switch SW from its normal position closes at contact a of switch circuit controller SWC a circuit path in multiple with contact PDLa, but the circuit for supplying direct current to winding W2 of reactor SRA and the winding of relay TESRA, having already been completed through contact PDLa, the completion of this multiple circuit performs no function at this time.

For a train movement from the main track through switch SW in its reverse position and into the siding track, the operation of the apparatus is similar to that just described except, of course, the track circuit of track section T is already shunted by the wheels and axles of the train on the rails of the track section.

If switch SW is out of adjustment and creeps from its normal position, or is not returned to its full normal position after an operation thereof, contact a of switch circuit controller SWC will close the circuit to supply direct current to winding W2 of reactor SRA and shunt the track circuit in the same manner as when contact PDLa was actuated by removal of the padlock. This action will release track relay TR and control signal S to display its red aspect to indicate to a train that a condition of danger exists. However, timing relay TER will not be actuated and the switch will not be electrically unlocked as these control circuits will remain open at padlock actuated contact PDLb.

It is, therefore, apparent that with apparatus and circuit arrangement as shown in FIG. 1, I have shown a method for shunting an alternating current track circuit,

at an outlying switch provided with a switch lock, in electric propulsion territory, without the use of switch circuit controller or padlock actuated heavy-duty contacts. I have also shown a method for checking that the en ergy, for controlling the application of the track circuit shunt, is supplied to the shunting apparatus before the switch can be electrically unlocked.

A further examination of the arrangement of FIG. 1 will disclose that, if the control winding W2 of reactor SRA becomes short-circuited, relay TESRA could be energized and an electrical unlock of the switch obtained without shunting the track circuit of track section T. While this possibility is rather remote, most railroads in the United States demand that signaling systems be on the fail-safe principle insofar as possible, and the modification shown in FIG. 2 was designed to overcome improper operation of the apparatus in the event of occurrence of the aforesaid remote possibility.

Referring to FIG. 2, the arrangement shown is similar to that of FIG. 1 except that the saturable reactor SRB is provided with an additional winding W3 which is connected to the control terminals of a first or pick-up winding P of a double wound relay TESRB. A contact b of this relay is included in the control circuits for timing relay TER and switch lock control winding WLK. Winding W3 is arranged on the core of reactor SRB so as to be in an inductive relationship with winding W2.

The operation of winding W2 and relay TESRA is identical to that previously described for the arrangement of FIG. 1, and no further description of the operation of this apparatus is believed necessary. It will, therefore, be expedient to describe the operation of winding W3 and relay TESRB.

When direct current is supplied to winding W2 by the closing of contact PDLa (or contact a of circuit controller SWC), a momentary pulse of energy is induced in winding W3. The winding W3 and pick-up winding P of relay TESRB are so proportioned that the induced pulse of energy is sutficient to momentarily pick up relay TESRB. The picking up of relay TESRB completes a stick circuit to the second or holding winding H of that relay over its own front contact a, and the relay is thus maintained in the picked up position. This stick circuit may be traced from battery terminal B through contact a of padlock actuated contact PDL (or contact a of switch circuit controller SWC), front contact a of relay TESRB and winding H of relay TESRB to battery terminal N. When, therefore, relay TESRB is picked up by energy induced in winding W3, it is maintained in that position until the padlock is replaced and the switch is returned to its normal position. The front contact 11 of relay TESRB in the control circuits for relay TER and switch lock winding WLK thus insures insofar as possible that winding W2 is not short-circuited and that the track circuit of track section T is shunted before an electric unlock of the switch can be obtained. Relay TESRA insures a continuous check that the direct current is being supplied to the control winding W2 of the saturable reactor to effect the track shunt. It should also be pointed out that Winding W3 of reactor SRB is self-checking, the picking up of relay TESRB being impossible if winding W3 is open or short circuited.

Referring now to FIG. 3, there is shown a modification of the apparatus of my invention similar to FIG. 2 but in which relay TESRA is eliminated. In the modification of FIG. 3 relay TESRC performs the functions performed by both relays TESRA and TESRB in the modification of FIG. 2.

When contact PDLa is closed by removal of the padlock from the switch SW (or when contact a of switch circuit controller SWC closes) a circuit is completed to apply direct current energy to winding W2 of reactor SRB. This circuit may be traced from battery terminal B through contact PDLa (or contact a of SWC), winding W2, back contact a of relay TESRC, and back con tact b of relay TER to battery terminal N. The integrity of this traced circuit is checked by the inductive winding W3 of reactor SRB and, if the circuit is intact, relay TESRC is picked up by the energy induced in winding W3 and supplied to the pick-up winding P of relay TESRC. The traced circuit also controls the shunt across the track rails of track section T, as previously described.

Contact a of relay TESRC constitutes what is commonly called a make-before-break, overlapping, or continuity contact. In the manner used here front contact a is normally open, but, when relay TESRC picks up, closes before back contact a opens. When relay TESRC has completely picked up, back contact a is open. When relay TESRC is picked up by the inductive energy supplied to its winding P, front contact a of relay TESRC closes before back contact a opens and thus maintains the supply of unidirectional shunting current to control winding W2. When back contact a of TESRC opens, the circuit path to back contact b of relay TER and battery terminal N is opened, and the stick circuit path through front contact a and holding winding H of relay TESRC can now function to maintain relay TBS-RC picked up.

It is to be noted thatthe described energizing circuit for winding W2 of reactor SRB checks that back contact b of relay TER is closed before the beginning of a timing cycle. This insures that a full timing period is obtained before an electric unlock of switch SW is accomplished.

The circuits for energization of timing relay TER and the switch lock winding WLK are similar to those described for FIGS. 1 and 2 and no detailed tracing thereof is believed necessary.

While in each of the FIGS. 1, 2 and 3, I have shown the use of a saturable reactor having a core with four legs, it is to be understood that the reactor may take different forms without departing from the scope of my invention.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is to be further understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway traffic control system, in combination, a section of railway track extending between a first location and a second location, a track circuit for said section of railway track including a source of alternating current normally supplied to the rails of said track section at said first location, a normally energized track relay connected across the rails of said track section at said second location, a trafiic controlling device at said second location and controlled by a circuit through a front contact of said track relay, a manually operable track switch located within said railway track section, a padlock for said track switch, an electrically controlled switch lock for said track switch, a saturable reactor having a first winding arrangement connected in multiple with said track clrcuit and so proportioned to normally present a high reactance to said alternating current of said track circuit, a source of unidirectional current of a predetermined value, a control winding for said reactor and so proportioned and arranged in relationship to said first winding arrangement that said reactance of the first winding arrangement is sufficiently lowered to shunt said track circuit when said unidirectional current of a predetermined value is supplied to said control winding, a checking relay connected in series with said control winding, means controlled by said padlock for supplying said unidirectional current to said control winding and said checking relay when said padlock is removed from said track switch, means controlled by said switch for supplying said unidirectional current to said control winding and said checking relay when said track switch is in other than its normal positioma timing relay, means controlled by said padlock and said checking relay for energizing said timing relay when said padlock is removed from said track switch and said checking relay is picked up, and means including a contact of said timing relay for unlocking said switch lock when and only when the timing period of said timing relay has expired.

2. In a railway trafiic control system, in combination, a section of railway track eXtending between a first location and a second location, a track circuit for aid section of railway track including a source of alternating current normally supplied to the rails of said track section at said first location, a normally energized track relay connected across the rails of said track section at said second location, a traffic controlling device at said second location and controlled by a circuit through a front contact of said track relay, a manually operable track switch located within said railway track section, a padlock for said track switch, normally open contacts associated with said padlock and operated to a closed position only when said padlock is removed from said track switch, a circuit controller associated with said track switch and having a normally open contact operated to a closed position when said track switch occupies other-than its normal position, an electrically controlled switch lock for said track switch, a control winding for said switch lock, a saturable reactor having two series connected main windings connected in multiple with said track circuit and so proportioned to normally present a high reactance to said alternating current of said track circuit, a source of unidirectional current of a predetermined value, a control winding for said reactor and so proportioned and arranged in relationship to said main windings that said reactance of the main windings is sufficiently lowc"ed to short-circuit said alternating current when said u irectional current of a predetermined value is supplied to said control winding, a checking relay connected in series with said control winding, a timing relay; a circuit including a back contact of said timing relay, and said switch circuit controller contact in multiple with one of said padlock operated contacts, for supplying said unidirectional current to said control winding and said checking relay; a stick circuit for said checking relay including one of its own front contacts, an energizing circuit for said timing relay including a second of said padlock contacts and a front contact of said checking relay, and a circuit for energizing said control winding of said switch lock and including a front contact of said timing relay.

3. in a railway trafiic control system, in combination, a section of railway track extending between a first location and a second location, a track circuit for said section of railway track including a source of alternating current normally supplied to the rails of said track section at said first location, a normally energized track relay connected across the rails of said track section at said second location, a tralfic controlling device at said second location and controlled by a circuit through a front contact of said track relay, a manually operable track switch located within said railway track section, a padlock for said track switch, an electrically controlled switch lock for said track switch, a saturable reactor having a first winding arrangement connected in multiple with said track circuit and so proportioned to normally present a high reactance to said alternating current of said track circuit, a source or. unidirectional current of a predetermined value, a control winding for said reactor and so proportioned and arranged in relationsip to said first winding arrangement that said reactance of the first winding arrangement is sufficiently lowered to shunt said track circuit when said unidirectional current of a predetermined value is supplied to said control winding, a first checking relay connected in series with said control winding, a checking winding for said reactor arranged in inductive relationship to said control winding, a second checking relay connected to the terminals of said checking winding, means controlled by said padlock for supplying said unidirectional current to said control winding and said first checking relay when said padlock is removed from said track switch, means controlled by said track switch for supplying said unidirectional current to said control winding and said first checking relay when said track switch is in other than its normal position, a timing rcla means controlled by said padlock and said checking relays for energizing said timing relay when said padlock is removed from said track switch and said first and second checking relays are picked up, and means including a contact of said timing relay for unlocking said switch lock when and only when the timing period of said timing relay has expired.

4. In a railway traffic control system, in combination, a section of railway track extending between a first location and a second location, a track circuit for said section of railway track including a source of alternating current normally supplied to the rails of said track section at said first location, a normally energized track relay connected across the rails of said track section at said second location, a traffic controlling device at said second location and controlled by a circuit through a front Contact of said track relay, a manually 013613: ble track switch located within said railway track section, a padlock for said track switch, normally open contacts associated with said padlock and operated to a closed position only when said padlock is removed from said track switch, a circuit controller associated with said track switch and having a normally open contact operated to a closed position when said track switch occupies other than its normal position, an electrically controlled switch lock for said track switch, a control winding for said switch lock, a saturable reactor having two series connected main windings connected in multiple with said track circuit and so proportioned to normally present a high reactance to said alternating current of said track circuit, a source of unidirectional current of a predetermined value, a control winding for said reactor and so proportioned and arranged in relationship to said main windings that said reactance of the main windings is sufficiently lowered to short-circuit said alternating current when said unidirectional current of a predetermined value is supplied to said control winding, a first checking relay connected in series with said control winding, a checking winding for said reactor and arranged in inductive relationship with said control winding, a double winding second checking relay having one of its windings connected to the terminals of said checking winding, a timing relay; a circuit including a back contact of said timing relay, and said switch circuit controller contact in multiple with one of said padlock operated contacts, for supplying said unidirectional current to said control winding and said first checking relay; a stick circuit for said first checking relay including one of its own front contacts, a stick circuit for said second checking relay including one of its own front contacts and its other winding; an energizing circuit for said timing relay including a second of said padlock contacts, a front contact of said first checking relay and a front contact of said second checking relay; and a circuit for energizing said control winding of said switch lock and including a front contact of said timing relay.

5. In a railway trafiic control system, in combination, a section of railway track extending between a first location and a second location, a track circuit for said section of railway track including a source of alternating current normally supplied to the rails of said track section at said first location, a normally energized track relay connected across the rails of said track section at said second location, a traffic controlling device at said second location and controlled by a circuit through a front contact of said track relay, a manually operable track switch located within said railway track section, a padlock for said track switch, an electrically controlled switch lock for said track switch, a saturable reactor having a first winding arrangement connected in multiple with said track circuit and so proportioned to normally present a high reactance to said alternating current of said track circuit, a source of unidirectional current of a predetermined value, a control winding for said reactor and so proportioned and arranged in relationship to said first winding arrangement that said reactance of the first winding arrangement is sufliciently lowered to shunt said track circuit when said unidirectional current of a predetermined value is supplied to said control winding, a checking winding for said reactor arranged in inductive relationship to said control winding, a checking relay connected to the terminals of said checking winding, means controlled by said padlock for supplying said unidirectional current to said control winding when said padlock is removed from said track switch, means controlled by said track switch for supplying said unidirectional current to said control winding when said track switch is in other than its normal position, a timing relay, mean-s controlled by said padlock and said checking relay for energizing said timing relay when said padlock is removed from said track switch and said checking relay is picked up, and means including a contact of said timing relay for unlocking said switch lock when and only when the timing period of said timing relay has expired.

6. In a railway traffic control system, in combination, a section of railway track extending between a first location and a second location, a track circuit for said section of railway track including a source of alternating current normally supplied to the rails of said track section at said first location, a normally energized track relay connected across the rails of said track section at said second location, a trafiic controlling device at said second location and controlled by a circuit through a front contact of said track relay, a manually operable track switch located Within said railway track section, a padlock for said track switch, normally open contacts associated with said padlock and operated to a closed position only when said padlock is removed from said track switch, a circuit controller associated with said track switch and having a normally open contact operated to a closed position when said track switch occupies other than its normal position, an electrically controlled switch lock for said track switch, a control winding for said switch lock, a saturable reactor having two series connected main windings connected in multiple with said track circuit and so proportioned to normally present a high reactance to said alternating current of said track circuit, a source of unidirectional current of a predetermined value, a control winding for said reactor and so proportioned and arranged in relationship to said main windings that said reactance of the main windings is sufliciently lowered to short-circuit said alternating current when said unidirectional current of a predetermined value is supplied to said control winding, a checking winding for said reactor arranged in inductive relationship with said control winding, a double winding checking relay having one of its windings connected to the terminals of said checking winding, a timing relay; a circuit including a back contact of said timing relay, and said switch circuit controlled contact in multiple with one of said padlock contacts, for supplying said unidirectional current to said control winding; a stick circuit for said checking relay including one of its own front contacts and its other winding, an energizing circuit for said timing relay including a second of said padlock contacts and a front contact of said checking relay, and a circuit for energizing said control winding of said switch lock and including a front contact of said timing relay.

7. In a railway traflic controlling system in electric railway propulsion territory including a manually operable track switch provided with a switch lock located within a section of railway track provided with an alternating current track circuit including the rails of the track section, a source of alternating current connected across the rails, and a normally energized track relay connected across the rails; the combination comprising, a core of saturable material; a first Winding arrangement mounted on the core and having one of its terminals connected directly to one of said rails and its other terminal connected directly to the other of the rails, said Winding arrangement and core being proportioned to normally provide a reactance to the alternating current of the track circuit above that which will cause said relay to release; a second winding mounted on said core and proportioned so that when a unidirectional current of a predetermined value is supplied to the second winding the reactance of said first winding arrangement is sufficiently lowered that the first winding arrangement will cause said relay to release, a checking relay, a circuit controller having a normal and an actuated position, means controlled by the circuit controller for energizing said second winding and the winding of the checking relay with unidirectional current of said predetermined value when the circuit controller is moved to its actuated position, means controlled by the checking relay for unlocking said switch lock when and only when the checking relay is picked up, a trafiic controlling device for governing the movements of trains over said track section, and means controlled by said track relay for controlling said device in accordance with the picked up or released condition of the track relay.

8. In combination with a manually operable track switch provided with an electric switch lock and a padlock for normally maintaining said switch in a locked condition, said switch being located within a section of railway track provided with an alternating current track circuit including the rails of the track section, a source of alternating current connected across said rails, and a normally energized track relay connected across the rails; two series connected windings mounted on a core of saturable material and connected in multiple with said track circuit, said windings and core being proportioned so that the windings normally present a sufliciently high reactance to the alternating current of the track circuit that only a value of alternating current less than that necessary to cause release of the track relay will normally flow through the windings; a third winding mounted on said core and proportioned so that when a unidirectional current of a predetermined value is supplied to said third winding the reactance of said two windings is sufiiciently lowered that sufficient alternating current will fiow through said two windings to cause release of the track relay, a normally deenergized checking relay, means controlled by said padlock for supplying unidirectional current of said predetermined value to said third winding and the winding of said checking relay when the padlock is removed from the track switch, means controlled by said track switch for supplying unidirectional current of said predetermined value to said third winding and the winding of said relay when the track switch occupies other than its normal position, means controlled by said checking relay for unlocking said electric switch lock when said checking relay is picked up; and means for controlling the movement of trafiic over said track section, said means being controlled by said track relay.

9. In a railway traffic control system including a manually operable track switch provided with a switch lock located within a section of railway track provided with an alternating current track circuit including the rails of said track section, a source of alternating current connected across the rails, and a normally energized track relay having its winding connected across the rails; the combination comprising, a core of a saturable material; two series connected windings mounted on said core and connected in multiple with said track circuit, said windings being proportioned to normally present a high reactance to the alternating current of the track circuit; a third Winding mounted on said core and proportioned so that when a unidirectional current of a predetermined value is supplied to the third winding the reactance of said two windings is sufficiently lowered that they will stunt said track circuit, a checking relay connected in series with said third winding, a circuit controller having normal and ctuated positions, means controlled by said circuit controller for supplying said unidirectional current to said third winding and said checking relay when the circuit controller occupies its actuated position, means controlled by said checking relay for unlocking said switch look when the checking relay is energized, and traffic controlling means for controlling the movement of traffic over said track section and controlled by said track relay.

10. In a railway traflic control system including a manually operable track switch provided with a switch lock located within a section of railway track provided with an alternating current track circuit including the rails of said track section, a source of alternating current connected across the rails, and a normally energized track relay having its winding connected across the rails; the combination comprising, a core of a saturable material; two series connected windings mounted on said core and connected in multiple with said track circuit, said windings being proportioned to normally present a high reactance to the alternating current of the track circuit; a third winding mounted on said core and proportioned so that when a unidirectional current of a predetermined value is supplied to the third winding the reactance of said two windings is SUffiClBl'llly lowered that they will shunt said track circuit, a fourth winding mounted on said core in inductive relationship to said third winding, a checking relay connected in series with said fourth winding, a circuit controller having normal and actuated positions, means controlled by said circuit controller for supplying said unidirectional current to said third winding when the circuit controller is moved to its actuated position, means controlled by said checking relay for unlocking said switch lock when the checking relay is picked up, and trafiic controlling means for controlling the movement of trafiic over said track section and controlled by said track relay.

ll. In a control arrangement for an electric switch lock applied to an outlying track switch located within a section of railway track provided with an alternating current track circuit including the rails of the section and a source of alternating current connected across the rails, the combination comprising, a first winding arrangement mounted on a core of saturable material and connected in multiple with said track circuit, a second winding mounted on said core and proportioned to sufliciently lower the reactance of said first winding arrangement that the first winding shunts the track circuit when a unidi rectional current of a predetermined value is supplied to the second winding, a relay connected in series with said second winding, a circuit controller, means controlled by said circuit controller for at times supplying a unidirectional current of said predetermined value to said second winding and said relay, and means controlled by said relay for energizing the control winding of said electric switch lock when the relay is picked up.

12. In a control arrangement for an electric switch lock applied to an outlying track switch located within a section of railway track provided with an alternating current track circuit including the rails of the section and a source of alternating current connected across the rails, the combination comprising, a first winding arrangement mounted on a core of a saturable material and connected in multiple with said track circuit, a second winding mounted on said core and proportioned to sufiiciently lower the reactance of said first winding arrangement that the first winding shunts the track circuit when a unidirectional current of a predetermined value is supplied to the second winding, a third winding mounted on said core in an inductive relationship to said second winding, a relay connected in series with said third winding, a circuit controller, means controlled by said circuit controller for at times supplying a unidirectional current of said predetermined value to said second winding, and means controlled by said relay for energizing the control winding of said electric switch lock when the relay is picked up.

References Cited in the file of this patent UNITED STATES PATENTS 1,638,043 Lee Aug. 9, 1927 2,049,859 OHagan Aug. 4, 1936 2,057,159 OHagan Oct. 13, 1936 2,517,280 Bone Aug. 1, 1950 

